Internal mold release agents used in the production of molded polyurethane and polyurea products are known. Many of the known internal release agents are based at least in part on fatty acid esters. Typical of such release agents are those described in U.S. Pat. Nos. 3,726,952, 3,925,527, 4,058,492, 4,098,731, 4,201,847, 4,254,228, 4,868,224 and 4,954,537, and British Patent 1,365,215.
U.S. Pat. Nos. 4,519,965 and 4,581,386 describe the use of zinc carboxylates as internal mold release agents for the production of molded polyurethane and/or polyurea elastomers.
While these types of internal release agents have met with some success, they are not totally satisfactory for many applications. Two shortcomings of all internal release agents to date, including those described above, are i) the inability to release from a bare metal mold, such as steel or aluminum, and ii) the incompatibility of such agents with other additives typically used in the reaction injection molding ("RIM") process.